Hundreds of South Koreans have clashed with security forces in a village where the U.S. military is to start installing launchers of the U.S. anti-missile system designed to protect them against mounting threats from North Korea.

Police sent thousands of officers to remove several hundred protesters who were blocking a road to a former golf course where the Terminal High-Altitude Area Defense (THAAD) System has been set up.

An official in rural Seonju said Thursday that 38 people, including six police officers, were injured in the clashes.

Seonju residents and activists have raised concerns over rumored health hazards linked to the system’s powerful radar and the possibility the town will become a target of North Korean attacks.

The THAAD is thought to be the world’s most advanced interceptor. It is designed to shoot down short- to medium-range missiles midflight as they approach a target.

South Korea’s defense ministry has said the deployment is necessary because of the imminent threat from North Korea, which has launched numerous missiles since South Korean President Moon Jae-in took office in early May.

North Korea also conducted its sixth nuclear test Sunday, drawing a sharp response from South Korea, Japan, the United States and the United Nations. Pyongyang’s relentless pursuit of nuclear arms has raised tensions on the Korean Peninsula and beyond.